In short: Yes - the device immediately shows the temperature and humidity on the display, you can set it up without a hub and read the values.

Details: The Tapo T315 has a built-in E-Ink/display that shows temperature, humidity, comfort indicator and battery status; after inserting the two AAA batteries, the readings appear directly on the display. However, TP-Link points out that the Tapo hub is required for "smart functions" such as remote monitoring, data storage/export, notifications and automations; these functions will not work without the hub.

Note on measurement: The measurement accuracy is typically ±0.3 °C and ±3 % RH, data is updated approximately every 2 seconds. If you want to use the device purely as a local reference device without app/remote access, a hub is not necessary.